A system may comprise a sensor configured to measure a characteristic of an engine component. A valve assembly may have an airflow outlet in fluid communication with the engine component. The valve assembly may include a first valve. A first valve control device may be coupled to the first valve and configured to control the first valve based on a measurement by the sensor. A second valve may be in fluidic series with the first valve. A second valve control device may be coupled to the second valve and configured to control the second valve based on the measurement by the sensor.

A system may comprise a sensor configured to measure a characteristic of an engine component. A valve assembly may have an airflow outlet in fluid communication with the engine component. The valve assembly may include a first valve. A first valve control device may be coupled to the first valve and configured to control the first valve based on a measurement by the sensor. A second valve may be in fluidic series with the first valve. A second valve control device may be coupled to the second valve and configured to control the second valve based on the measurement by the sensor.

A gas turbine engine and methods of operation include a low pressure electric motor-generator arranged for selective operation in a generator mode to generate electrical power or a drive mode to assist rotation of a low pressure drive shaft of the engine.

A method and associated control device for synchronizing a turbine with an alternating current network having a network frequency, having the following steps: A) accelerating the turbine up to a frequency in the range of the network frequency; B) sensing an angle difference between the turbine and the alternating current network; C) sensing a speed difference between the turbine and the alternating current network; D) accelerating or decelerating the turbine such that the turbine follows a desired trajectory, wherein the desired trajectory is a trajectory calculated in advance that indicates, in dependence on the angle difference, a desired speed difference that should be present such that a target angular position between the turbine and the alternating current network suitable for synchronous feed-in is achieved when the speed of the turbine and the speed of the alternating current network correspond.

A method and associated control device for synchronizing a turbine with an alternating current network having a network frequency, having the following steps: A) accelerating the turbine up to a frequency in the range of the network frequency; B) sensing an angle difference between the turbine and the alternating current network; C) sensing a speed difference between the turbine and the alternating current network; D) accelerating or decelerating the turbine such that the turbine follows a desired trajectory, wherein the desired trajectory is a trajectory calculated in advance that indicates, in dependence on the angle difference, a desired speed difference that should be present such that a target angular position between the turbine and the alternating current network suitable for synchronous feed-in is achieved when the speed of the turbine and the speed of the alternating current network correspond.

A device for controlling positioning of variable-geometry equipment of a turbomachine, including a computer, an actuator of variable geometry driven by the computer, and a drive train, the actuator including moving parts including a sensor for measuring its elongation, the drive train being connected at one of its ends to a point of attachment of the moving parts and at another end to a point of attachment of the equipment, the point of attachment moving under action of the actuator along a travel limited by an end stop and the drive train being elastically deformable under the action of the actuator when the point of attachment is against the end stop. An elongation instruction supplied by the computer to the moving parts is defined as a difference with respect to the value of the elongation of the moving parts that corresponds to contact between the point of attachment and the end stop.

A device for controlling positioning of variable-geometry equipment of a turbomachine, including a computer, an actuator of variable geometry driven by the computer, and a drive train, the actuator including moving parts including a sensor for measuring its elongation, the drive train being connected at one of its ends to a point of attachment of the moving parts and at another end to a point of attachment of the equipment, the point of attachment moving under action of the actuator along a travel limited by an end stop and the drive train being elastically deformable under the action of the actuator when the point of attachment is against the end stop. An elongation instruction supplied by the computer to the moving parts is defined as a difference with respect to the value of the elongation of the moving parts that corresponds to contact between the point of attachment and the end stop.

A turbofan engine includes a first spool including a first turbine and a second spool including a second turbine. A superposition gear system includes a plurality of intermediate gears engaged to a sun gear and supported in a carrier and a ring gear circumscribing the intermediate gears. A second tower shaft is engaged to drive the sun gear. A starter is selectively coupled to the sun gear through a starter clutch. A first electric motor and a second electric motor are coupled to the superposition gear system and are operable to input power into a corresponding one of the first and second spools.

A turbofan engine includes a first spool including a first turbine and a second spool including a second turbine. A superposition gear system includes a plurality of intermediate gears engaged to a sun gear and supported in a carrier and a ring gear circumscribing the intermediate gears. A second tower shaft is engaged to drive the sun gear. A starter is selectively coupled to the sun gear through a starter clutch. A first electric motor and a second electric motor are coupled to the superposition gear system and are operable to input power into a corresponding one of the first and second spools.

In an aircraft gas turbine engine equipped with a bleed-off valve that bleeds intake air compressed by a compressor exterior and an electric actuator that drives the valve when current is supplied, a required valve opening θr and a current value Ia corresponding thereto are calculated and Ia is supplied to the actuator to bring valve opening θ to the required opening θr. Then Ia is compared with a current value Ib and if Ia exceeds 1b, the valve is estimated to have failed and another current value Ic is calculated and Ic is supplied to enlarge valve opening toward wide-opening θw. Then a current value Id is calculated and supplied to decrease valve opening toward θr. Next, Id is compared with Ib and the valve is determined normal when Id is equal to or smaller than 1b. If not, it is determined to be faulty.